Roll mark inspection apparatus

Abstract

A roll mark inspection apparatus for a system for rolling and moving a strip uses reduction rolls. An image sensor scans widthwise the strip which is rolled and moved by the reduction rolls and outputs an image signal representing a surface state of the strip per unit width. A clock generator generates a clock signal synchronized with the running of the strip moved by the reduction rolls. An autocorrelation calculator sequentially receives the image signal in synchronism with the clock signal, and performs a predetermined autocorrelation calculation processing on the contents of the received signal and outputs an autocorrelation value. A comparator compares a predetermined comparison value for discriminating information corresponding to a roll mark on the surface of the strip with the autocorrelation value, and outputs a roll mark signal discriminated from the autocorrelation value by the predetermined comparison value. A CRT display device updates and displays image information corresponding to the roll mark signal each time the strip runs by a predetermined distance corresponding to a circumferential length of the reduction rolls.

What is claimed is: 
     
       1. A roll mark inspection apparatus, which is applied to a system for rolling and moving a strip material using reduction rolls, comprising: surface state inspecting means for outputting an image signal representing a surface state of said strip material rolled and moved by said reduction rolls;   image information processing means connected to said surface state inspecting means for receiving the image signal output from said surface state inspecting means in synchronism with running of said strip material, performing predetermined processing to the received information, and outputting processed information;   comparing means connected to said image information processing means for comparing a predetermined comparison value, used to extract information corresponding to roll marks formed on the surface of said strip material by a speck of said reduction rolls, with the processed information output from said image information processing means, and outputting information discriminated from the processed information by the predetermined comparison value, and   display means connected to said comparing means for displaying an image corresponding to the discriminated information output from said comparing means each time said strip material runs by a predetermined distance corresponding to a circumferential length of said reduction rolls.   
     
     
       2. The apparatus according to claim 1, wherein said display means includes: clock signal generating means for generating a clock signal in synchronism with running of said strip material;   latch means for storing the discriminated information each time a predetermined number of the clock signals are generated; and   display device for displaying an image corresponding to the roll mark of said belt-like material on a basis of the information latched in said latch means.   
     
     
       3. The apparatus according to claim 1, wherein said comparing means includes: smoothing signal generating means for detecting an average value per predetermined running distance of said strip material of contents of the processed information output from said image information processing means, and generating a smoothed signal corresponding to the detected average value;   detection level generating means for generating from the smoothed signal a roll mark detection level which changes in correspondence with signal components not caused by the roll mark of the image signal representing the surface state of said strip material; and   supplying means for comparing the contents of the processed information with the roll mark detection level, and supplying a comparison result as the discriminated information to said display means.   
     
     
       4. The apparatus according to claim 1, wherein said surface state inspecting means includes: image sensor means for scanning the surface of said strip material widthwise, and outputting a surface state signal representing the surface state;   binary set level generating means for generating a binary set level which changes in correspondence with a noise signal component included in the surface state signal from said image sensor means; and   means for producing a binary form of the surface state signal and outputting the image signal on a basis of the binary set level.   
     
     
       5. The apparatus according to claim 1, wherein said display means includes: a direct-view display device for displaying an image corresponding to the roll mark of said strip material on the basis of a discriminated information output from said comparing means; and   a scale, mounted on a display screen of said direct-view display device, for reading one of points and a period of the generated roll mark.   
     
     
       6. The apparatus according to claim 1, wherein said image information processing means includes: an autocorrelation function converting means for converting information corresponding to the image signal represented as a function f(t) into an autocorrelation function φ(τ) τ corresponding to a circumferential length of said reduction roll, the autocorrelation function φ(τ) being substantially represented by either of the following equations assuming that an interval for obtaining the autocorrelation is T: ##EQU6## and the processed information being output from said autocorrelation function converting means.   
     
     
       7. The apparatus according to claim 6, wherein said image signal processing means further includes: converting means for converting the image signal in a form of serial data into parallel image data; and   memory means for sequentially storing the parallel image data in synchronism with running of said strip material, the image signal and the parallel image data read out from said memory means being supplied as input data of autocorrelation function calculation to said autocorrelation function converting means.   
     
     
       8. The apparatus according to claim 6, wherein said image information processing means includes: image memory means for storing image information included in the image signal and representing a predetermined range on the surface of said strip material, the image information read out from said image memory means being supplied to said autocorrelation function converting means.   
     
     
       9. The apparatus according to claim 6, wherein said image information processing means includes: image memory means for storing two-dimensional image information included in the image signal and representing a predetermined range on the surface of the strip material; and   compensating means for performing compensating processing for substantially removing a periodic change included in the image signal from the two-dimensional image information read out from said image memory means, and supplying the compensated information to said autocorrelation function converting means.   
     
     
       10. The apparatus according to claim 1, wherein said display means includes: means for one of two-dimensionally and three-dimensionally displaying the information corresponding to the image signal.   
     
     
       11. A roll mark inspection apparatus which is applied to a system for rolling and moving a strip material using reduction rolls, comprising: first means for scanning widthwise said strip material rolled and moved by said reduction rolls, and outputting a first signal representing a surface state of said strip material;   second means for generating a second signal synchronized with running of said strip material moved by said reduction rolls;   third means for sequentially receiving the first signal in synchronism with the second signal, and outputting a third signal obtained by performing predetermined autocorrelation calculation processing to contents of the received signal;   fourth means for comparing a predetermined comparison level for discriminating information corresponding to a roll mark on the surface of said strip material with the third signal, and outputting a fourth signal discriminated from the third signal by the predetermined comparison value; and   fifth means for updating and displaying image information corresponding to the fourth signal each time said strip material runs by a predetermined distance corresponding to a circumferential length of said reduction rolls.   
     
     
       12. The apparatus according to claim 11, wherein said fifth means includes: clock signal generating means for generating a clock signal in synchronism with running of said strip material;   latch means for storing the fourth signal each time a predetermined number of clock signals are generated; and   display device for displaying an image corresponding to the roll mark of said strip material on a basis of the fourth signal latched in said latch means.   
     
     
       13. The apparatus according to claim 11, wherein said fourth means includes: smoothing signal generating means for detecting an average value per predetermined running distance of said strip material of contents of the third signal output from said third means, and generating a smoothed signal corresponding to the detected average value;   detection level generating means for generating from the smoothed signal a roll mark detection level which changes in correspondence with signal components not caused by the roll mark of the first signal representing the surface state of said strip material; and   supplying means for comparing the contents of the third signal with the roll mark detection level, and supplying a comparison result as the fourth signal to said display means.   
     
     
       14. The apparatus according to claim 11, wherein said first means includes: image sensor means for scanning the surface of said strip material widthwise, and outputting a surface state signal representing the surface state;   binary set level generating means for generating a binary set level which changes in correspondence with a noise signal component including in the surface state signal from said image sensor means; and   means for producing a binary form of the surface state signal and outputting the first signal on a basis of the binary set level.   
     
     
       15. The apparatus according to claim 11, wherein said fifth means includes: a direct-view display device for displaying an image corresponding to the roll mark of said strip material on a basis of the fourth signal output from said fourth means; and   a scale, mounted on a display screen of said direct-view display device, for reading one of points and a period of the generated roll mark.   
     
     
       16. The apparatus according to claim 11, wherein said third means includes: an autocorrelation function converting means for converting information corresponding to the first signal represented as a function f(t) into an autocorrelation function φ(τ) corresponding to a circumferential length of said reduction roll, the autocorrelation function φ(τ) being substantially represented by either of the following equations assuming that an interval for obtaining the autocorrelation is T: ##EQU7## ##EQU8## and the third signal being output from said autocorrelation function converting means.   
     
     
       17. The apparatus according to claim 16, wherein said third means further includes: converting means for converting the first signal in a form of serial data into parallel image data; and   memory means for sequentially storing the parallel image data in synchronism with running of said strip material, the image signal and the parallel image data read out from said memory means being supplied as input data of autocorrelation function calculation to said autocorrelation function converting means.   
     
     
       18. The apparatus according to claim 16, wherein said third means includes: image memory means for storing image information included in the first signal and representing a predetermined range on the surface of said strip material, the image information read out from said image memory means being supplied to said autocorrelation function converting means.   
     
     
       19. The apparatus according to claim 16, wherein said third means includes: image memory means for storing two-dimensional image information included in the first signal and representing a predetermined range on the surface of the strip material; and   compensating means for performing compensating processing for substantially removing a periodic change included in the first signal from the two-dimensional image information read out from said image memory means, and supplying the compensated information to said autocorrelation function converting means.   
     
     
       20. The apparatus according to claim 11, wherein said display means includes: means for one of two-dimensionally and three-dimensionally displaying the information corresponding to the first signal.   
     
     
       21. A roll mark inspection apparatus which receives roll mark data from an inspection head for scanning widthwise a strip running material rolled and moved by rolls and stores the roll mark data in an image memory having a storage area corresponding to a circumferential length of said rolls, sequentially reads out the roll mark data stored in said memory in synchronism with a running rate of said strip running material to calculate an autocorrelation value, and compares the autocorrelation value with a set value by a comparator, thereby inspecting a periodic roll mark formed on said strip running material, comprising: a sync signal generator for generating a sync signal synchronized with the running rate of said strip running material;   latch means connected to said sync signal generator for receiving the sync signal from said sync signal generator to detect that said strip running material runs by the roll circumferential length, and latching a comparison result output from said comparator; and   display means connected to said latch means for causing a CRT display device to display the comparison result output latched by said latch means as one raster.   
     
     
       22. A roll mark inspection apparatus which receives roll mark data from an inspection head for scanning in a width direction a strip running material rolled and moved by rolls and stores the roll mark data in an image memory having a storage area corresponding to a circumferential length of said rolls, calculates an autocorrelation value of the roll mark data obtained in a predetermined inspection length in a running direction of said strip running material, and converts the autocorrelation value into a binary value in accordance with a roll mark detection level by a comparator, thereby inspecting a periodic roll mark formed on said strip running material by a roll mark present on the surface of said rolls, comprising: a smoother for smoothing the autocorrelation value obtained in the predetermined inspection length; and   a roll mark detection level generator connected to said smoother for multiplying a smoothed output from said smoother with a predetermined number, and supplying the multiplied output as a roll mark detection level corresponding to a background power level to said comparator.